The present invention relates to an xDSL (any types of Digital Subscriber Line) accommodation apparatus, multicast distribution system, and data distribution method, which can avoid waste of the band of a relay line used to distribute a live content and reduce the installation cost of live content distribution.
Along with the recent remarkable development of the Internet, not only E-mail (Electronic mail) or WWW (World Wide Web) browsers but also broadcast-type live content stream distribution services are also appearing. This is mainly due to the advent of broadband access means represented by xDSL. However, conventional methods used for broadcast-type live content stream distribution services for xDSL subscribers, i.e., a general content download method, a method using IP (Internet Protocol) multicast, and a method of using a splitter have the following problems.
A conventional distribution system used not only for content download but also for stream distribution will be described with reference to FIG. 10. A Web server 10 individually distributes live contents having the same contents to a client (A) 80, client (B) 81, and client (C) 82 as packet data. The live contents are distributed from a router 20 to the clients 80 to 82 through an IP network 30, BAS (Broadband Access Server) 40, ATM (Asynchronous Transfer Mode) access network 50, xDSL accommodation apparatus 60, and xTU-Rs (any types of Transmission Unit Remotes) 70, 71, and 72. In this distribution system, the band of the relay line from the router 20 to the BAS 40, ATM access network 50, and xDSL accommodation apparatus 60 through the IP network 30 is wasted.
In a conventional IP multicast distribution system shown in FIG. 11, a router 21 and IP network 31 cope with multicast. A content server 11 only needs to transmit a signal packet having an M (multicast) address. In this scheme, the configuration becomes complex because the router 21 and IP network 31 on the route must cope with multicast. In addition, the problem that the band of the relay line up to a BAS 40, ATM access network 50, and xDSL accommodation apparatus 60 is wasted is not solved.
In a conventional multicast distribution scheme using a splitter shown in FIG. 12, a splitter 90 is arranged in an IP network 30 near a server 11. Since this splitter 90 copies/distributes a single packet to clients (A) to (C) that are reserved in advance, a router 20 and the IP network 30 need not cope with multicast. In addition, the content server 11 only needs to transmit a signal packet having a D address to the splitter 90. In this scheme, however, the problem that the band of the relay line up to a BAS 40, ATM access network 50, and xDSL accommodation apparatus 60 is wasted is not solved.
As described above, for the broadcast-type live content stream distribution services, the methods using IP multicast or a splitter are proposed to reduce wasteful use of the relay line in general stream distribution. However, both the methods have problems in capital investment and effective use of the relay line.